Salt Marsh Birds Threatened by Sea-Level Rise

Saltmarsh Sparrow. Photo: George Jett

Species of marsh birds such as the Clapper Rail, Virginia Rail, Willet, Seaside Sparrow and Marsh Wren could experience 80% population declines in the Chesapeake Bay region if sea-levels rise by three to six feet by the year 2100. The analysis by the Center for Conservation Biology of the College of William and Mary found that sea-level rise will be particularly harmful to Black Rail and Saltmarsh Sharp-tailed Sparrow that rely solely on irregularly flooded high marsh. The scientists’ simulation found that many of the known breeding sites of these species would be completely inundated by rising waters.

Sea-level rise is a particularly acute problem for the Chesapeake Bay, which is already losing marshland twice as fast as the global average due to natural subsidence caused by movement in the North American plate. The region supports about 30% of the salt marsh along the Atlantic Coast, and 60% of the salt marsh north of the Carolinas.

The researchers simulated the loss of marshes from rising ocean waters, which are currently predicted to globally rise between a two and six feet by the end of this century. One question that remains is whether any sort of effective mitigation can be achieved that allows the salt marshes to move further inland. Many of these same areas are now developed and may demand hard barriers to keep the ocean at bay. This could squeeze salt marsh habitat out of existence, and with it, the many bird species that have evolved there. For more information see www.ccb-wm.org.

Another study has found that as much as half of California could be occupied by new bird communities by 2070, according to PRBO Conservation Science and other researchers. While the movement of individual species as result of climate change is already being documented, this study broke new ground by determining that entire new assemblages of birds are likely to result, with uncertain consequences. The study found that: “Predator-prey or competitive interactions may become affected as species assemblages are reshuffled in new ways…this may result in the decline or extirpation of species as they adjust or adapt to changing climates.” For more information see www.prbo.org.